The present disclosure relates to a heating unit, a fixing device, and an image forming apparatus.
An electrographic image forming apparatus includes a fixing device that thermally fixes toner on a medium.
For example, a heater of the fixing device is proposed. The heater has heating part that are arranged in a longer side direction and that generate heat when energized, and branching paths that are aligned at predetermined intervals in the longer side direction so as to energize the heating parts. The branching paths include first branching paths that diverge from conductive paths elongated from electrical contacts connected to one side of a power source, and second branching lines that diverge from the conductive paths at positions farther from the electrical contacts than the first branching paths. In the heater, resistance of the first branching lines is greater than that of the second branching lines, which restrains that heat generation decreases as farther from the electrical contacts under influence of a voltage drop due to electrical resistance of the conductive paths. In other words, uneven heating in the longer side direction of the heater is restrained by changing resistance of each branching line.